Answer: Sedge peat is also called peat humus (different from peat moss) and is often sold by the bag along with topsoil and similar products. It is not always available in all areas of the country however.
With regard to using it on roses, the better approach might be to run some basic soil tests and see how the pH and fertility measure up. Then, amend the soil based on the test results.
In general, roses prefer an evenly moist yet well drained soil that is high in organic matter such as compost, old rotted leaves or well rotted/aged stable manure/bedding. A clay or sandy soil can both be improved by adding organic matter. The soil structure is very important in keeping the roses healthy.
I hope this gives you some ideas on improving your soil for growing better roses. Also, I apologize that it has taken us so long to respond to your question.
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